@color: red;
li {
  width: 200px;
  height: 20px;
  list-style-type: none;
  &:nth-of-type(1) {
    background-color: darken(@color, 10%);
  }
  &:nth-of-type(2) {
    background-color: darken(@color, 20%);
  }
  &:nth-of-type(3) {
    background-color: darken(@color, 30%);
  }
  &:nth-of-type(4) {
    background-color: darken(@color, 40%);
  }
  &:nth-of-type(5) {
    background-color: darken(@color, 50%);
  }
  &:nth-of-type(6) {
    background-color: darken(@color, 60%);
  }
  &:nth-of-type(7) {
    background-color: mix(red, blue);
  }
}
